Digital Imager Enhancement and Investigating Grayscale Photomasks Technologies for Fabrication of Micro-optics

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New microfabrication techniques have had a dramatic impact on society, by transforming microchips into digital imaging sensors and micro-optics. From scientific instrumentation to commercial photography, imaging sensors are now used to integrate sensors with micro-optics and control electronics onto single chips. This proposed research combines the two areas of opto-electronics (the combination of electronics and optics) and nanofabrication, the technique used to build the micro-optics.******1) In opto-electronics my research group focuses on digital pixel arrays in cameras. Imagers develop a growing number of defects over time that degrades image quality and reduces the sensor life. Using commercial camera images, and software analysis algorithms, we study defect development to identify faulty pixels characteristics, and pinpoint the causal mechanism. Research will improve developed formulas that show the trend towards larger sensor area, higher sensitivity and shrinking pixel size creates exponential growth in both defect strength, and development rates, which can reach 1000's of defects per year. We will investigate applications such as novel ways to improve image repair based on software-correcting pixels that use knowledge about the defect parameters, creating parameters to give better metrics for choosing cameras in high radiation environments like the Space Station, and using these defect patterns and parameters to create a camera-unique "fingerprint" for forensic identification in security and criminal investigations.******2) In nanofabrication, we investigate the fabrication of grayscale photomasks, which are a technology critical to cost-effective 3D structures. Existing commercial grayscale masks are either very limited in transparency control or accurate but highly expensive. We are developing bimetallic thin films of Bismuth, Indium and Tin, forming a thermal resist which oxidizes and becomes transparent under laser exposure. With equipment that varies the laser power on these films, direct-write grayscale photomasks will be developed which the control transparency to a high accuracy (256 steps) in a low cost mask. Since mask transparency is only one limiting factor in the vertical control ability of microstructure, we will then combine this new mask with new fabrication methods to transfer these patterns into the creation of very accurate 3D structures for micro-optics. The micro-optic application requires highly precise shapes to create the proper optical images. Our research also intends to apply this method to the creation of micro-optics for applications in improving camera pixels, creating less distorting thin Fresnel lenses, and a thin Gabor lens for heads-up displays. In microfluidic designs, we will create 3D shapes in microchannels with unique fluid mixing properties and integrate micro-optics into fluorescence based lab-on-a-chip systems.